The development of robust chemical sensors for a range of analytes remains an important endeavor for applications such as environmental monitoring, product quality control, and chemical dosimetry. Among the many methods available for chemical sensing, calorimetric techniques remain advantageous in that the human eye can be used for signal transduction, rather than extensive instrumentation.
Though colorimetric sensors currently exist for a range of analytes, most are based upon employing dyes or colored chemical indicators for detection. Such compounds are typically selective, meaning arrays are necessary to enable detection of various classes of compounds. Moreover, many of these systems have lifetime limitation issues, due to photo-bleaching or undesirable side reactions. Other optical sensing techniques, such as surface plasmon resonance and spectral interferometry, require substantial signal transduction hardware to provide response, and thus are not useful for simple visual indication.